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NASA\u2019s Hubble Finds Water Vapor in Small Exoplanet\u2019s Atmosphere<\/h1>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n![\"\"](\"https:\/\/science.nasa.gov\/wp-content\/uploads\/2024\/01\/hubble-gj9827d-stsci-01hh2qj10qrvpjkmbfj252evpx.png?w=1920\")
<\/figure>\nThis is an artist\u2019s concept of the exoplanet GJ 9827d, the smallest exoplanet where water vapor has been detected in the atmosphere. The planet could be an example of potential planets with water-rich atmospheres elsewhere in our galaxy. With only about twice Earth\u2019s diameter, the planet orbits the red dwarf star GJ 9827. Two inner planets in the system are on the left. The background stars are plotted as they would be seen to the unaided eye looking back toward our Sun. The Sun is too faint to be seen. The blue star at upper right is Regulus; the yellow star at center bottom is Denebola; and the blue star at bottom right is Spica. The constellation Leo is on the left, and Virgo is on the right. Both constellations are distorted from our Earth-bound view from 97 light-years away.<\/div>\nNASA\/ESA\/Leah Hustak (STScI)\/Ralf Crawford (STScI)<\/div>\n<\/figcaption><\/div>\n<\/div>\n<\/div>\nAstronomers using NASA\u2019s Hubble Space Telescope<\/a> observed the smallest exoplanet where water vapor has been detected in the atmosphere. At only approximately twice Earth\u2019s diameter, the planet GJ 9827d could be an example of potential planets with water-rich atmospheres elsewhere in our galaxy.<\/p>\n\u201cThis would be the first time that we can directly show through an atmospheric detection, that these planets with water-rich atmospheres can actually exist around other stars,\u201d said team member Bj\u00f6rn Benneke<\/a> of the Trottier Institute for Research on Exoplanets<\/a> at Universit\u00e9 de Montr\u00e9al<\/a>. \u201cThis is an important step toward determining the prevalence and diversity of atmospheres on rocky planets.\u201d<\/p>\n\u201cWater on a planet this small is a landmark discovery,\u201d added co-principal investigator Laura Kreidberg<\/a> of Max Planck Institute for Astronomy<\/a> in Heidelberg, Germany. \u201cIt pushes closer than ever to characterizing truly Earth-like worlds.\u201d<\/p>\nHowever, it remains too early to tell whether Hubble spectroscopically measured a small amount of water vapor in a puffy hydrogen-rich atmosphere, or if the planet\u2019s atmosphere is mostly made of water, left behind after a primeval hydrogen\/helium atmosphere evaporated under stellar radiation.<\/p>\n
\u201cOur observing program<\/a>, led by principal investigator Ian Crossfield<\/a> of Kansas University<\/a> in Lawrence, Kansas, was designed specifically with the goal to not only detect the molecules in the planet\u2019s atmosphere, but to actually look specifically for water vapor. Either result would be exciting, whether water vapor is dominant or just a tiny species in a hydrogen-dominant atmosphere,\u201d said the science paper\u2019s<\/a> lead author, Pierre-Alexis Roy<\/a> of the Trottier Institute for Research on Exoplanets<\/a> at Universit\u00e9 de Montr\u00e9al<\/a>.<\/p>\n\u201cUntil now, we had not been able to directly detect the atmosphere of such a small planet. And we\u2019re slowly getting in this regime now,\u201d added Benneke. \u201cAt some point, as we study smaller planets, there must be a transition where there\u2019s no more hydrogen on these small worlds, and they have atmospheres more like Venus (which is dominated by carbon dioxide).\u201d<\/p>\n\n
<\/figure>Astronomers using NASA\u2019s Hubble Space Telescope<\/a> observed the smallest exoplanet where water vapor has been detected in the atmosphere. At only approximately twice Earth\u2019s diameter, the planet GJ 9827d could be an example of potential planets with water-rich atmospheres elsewhere in our galaxy.<\/p>\n \u201cThis would be the first time that we can directly show through an atmospheric detection, that these planets with water-rich atmospheres can actually exist around other stars,\u201d said team member Bj\u00f6rn Benneke<\/a> of the Trottier Institute for Research on Exoplanets<\/a> at Universit\u00e9 de Montr\u00e9al<\/a>. \u201cThis is an important step toward determining the prevalence and diversity of atmospheres on rocky planets.\u201d<\/p>\n \u201cWater on a planet this small is a landmark discovery,\u201d added co-principal investigator Laura Kreidberg<\/a> of Max Planck Institute for Astronomy<\/a> in Heidelberg, Germany. \u201cIt pushes closer than ever to characterizing truly Earth-like worlds.\u201d<\/p>\n However, it remains too early to tell whether Hubble spectroscopically measured a small amount of water vapor in a puffy hydrogen-rich atmosphere, or if the planet\u2019s atmosphere is mostly made of water, left behind after a primeval hydrogen\/helium atmosphere evaporated under stellar radiation.<\/p>\n \u201cOur observing program<\/a>, led by principal investigator Ian Crossfield<\/a> of Kansas University<\/a> in Lawrence, Kansas, was designed specifically with the goal to not only detect the molecules in the planet\u2019s atmosphere, but to actually look specifically for water vapor. Either result would be exciting, whether water vapor is dominant or just a tiny species in a hydrogen-dominant atmosphere,\u201d said the science paper\u2019s<\/a> lead author, Pierre-Alexis Roy<\/a> of the Trottier Institute for Research on Exoplanets<\/a> at Universit\u00e9 de Montr\u00e9al<\/a>.<\/p>\n \u201cUntil now, we had not been able to directly detect the atmosphere of such a small planet. And we\u2019re slowly getting in this regime now,\u201d added Benneke. \u201cAt some point, as we study smaller planets, there must be a transition where there\u2019s no more hydrogen on these small worlds, and they have atmospheres more like Venus (which is dominated by carbon dioxide).\u201d<\/p>\n